CVE-2026-80758
Received Received - Intake

Use-After-Free in Linux Kernel Futex Subsystem

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: futex: Avoid private hash use-after-free on final put futex_private_hash_put() drops the reference to fph before evaluating fph->mm for wake_up_var(). futex_ref_put() enables preemption again before returning. If that put drops the final reference and the task is preempted, another task can pivot to the replacement hash and free the old hash after an RCU grace period. The first task then reads fph->mm from the freed allocation when it resumes. KASAN reports a slab-use-after-free in futex_private_hash_put(), with the read at offset 24 in a freed kmalloc-512 allocation. The allocation and free stacks point to futex_hash_allocate() and the RCU free path, respectively. Load the mm pointer while the fph reference is still held and pass the saved value to wake_up_var(). wake_up_var() uses the pointer as a waitqueue key and does not dereference the mm through it.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-04
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80758
EUVD
EUVD-2026-71401

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's futex subsystem. It occurs when a task drops a reference to a futex hash structure before safely accessing its memory management pointer. If the task is preempted after dropping the reference, another task could free the hash, leading to a use-after-free when the first task later accesses the freed memory.

Detection Guidance

This vulnerability is specific to the Linux kernel and requires kernel-level detection. Check if your kernel version includes the fix by running uname -a and comparing against patched versions. Monitor kernel logs for slab-use-after-free errors related to futex operations.

Impact Analysis

This vulnerability could allow an attacker to cause a denial-of-service condition or potentially execute arbitrary code with kernel privileges. Successful exploitation may lead to system crashes or unauthorized access to sensitive data.

Mitigation Strategies

Update the Linux kernel to the latest patched version that includes the fix for this vulnerability. If immediate patching is not possible, consider disabling futex operations if they are not critical to your system's functionality.

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